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    <title>Document</title>
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    <script>
        var list=new Set([1,2,3]);
        /* 
        add添加一个值
        clear清除集合
        delete（value)可以删除集合中的某一元素
        forEach可以遍历集合
        has 判断集合是否拥有某个元素，返回boolean值
        */
        list.add(4,5);
        list.clear();
        list.delete(1);
        console.log(list.entrise())
        console.log(list)
    </script>
</body>
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